diff --git a/packages/core/src/config/models.test.ts b/packages/core/src/config/models.test.ts
index 8e6c3ea895..fd47d2a1ff 100644
--- a/packages/core/src/config/models.test.ts
+++ b/packages/core/src/config/models.test.ts
@@ -8,6 +8,7 @@ import { describe, it, expect } from 'vitest';
 import {
   resolveModel,
   resolveClassifierModel,
+  isGemini3Model,
   isGemini2Model,
   isAutoModel,
   getDisplayString,
@@ -25,6 +26,29 @@ import {
   DEFAULT_GEMINI_MODEL_AUTO,
 } from './models.js';
 
+describe('isGemini3Model', () => {
+  it('should return true for gemini-3 models', () => {
+    expect(isGemini3Model('gemini-3-pro-preview')).toBe(true);
+    expect(isGemini3Model('gemini-3-flash-preview')).toBe(true);
+  });
+
+  it('should return true for aliases that resolve to Gemini 3 when preview is enabled', () => {
+    expect(isGemini3Model(GEMINI_MODEL_ALIAS_AUTO, true)).toBe(true);
+    expect(isGemini3Model(GEMINI_MODEL_ALIAS_PRO, true)).toBe(true);
+    expect(isGemini3Model(PREVIEW_GEMINI_MODEL_AUTO)).toBe(true);
+  });
+
+  it('should return false for Gemini 2 models', () => {
+    expect(isGemini3Model('gemini-2.5-pro')).toBe(false);
+    expect(isGemini3Model('gemini-2.5-flash')).toBe(false);
+    expect(isGemini3Model(DEFAULT_GEMINI_MODEL_AUTO)).toBe(false);
+  });
+
+  it('should return false for arbitrary strings', () => {
+    expect(isGemini3Model('gpt-4')).toBe(false);
+  });
+});
+
 describe('getDisplayString', () => {
   it('should return Auto (Gemini 3) for preview auto model', () => {
     expect(getDisplayString(PREVIEW_GEMINI_MODEL_AUTO)).toBe('Auto (Gemini 3)');
diff --git a/packages/core/src/config/models.ts b/packages/core/src/config/models.ts
index 519f49c98e..9406fc4131 100644
--- a/packages/core/src/config/models.ts
+++ b/packages/core/src/config/models.ts
@@ -137,6 +137,20 @@ export function isPreviewModel(model: string): boolean {
   );
 }
 
+/**
+ * Checks if the model is a Gemini 3 model.
+ *
+ * @param model The model name to check.
+ * @returns True if the model is a Gemini 3 model.
+ */
+export function isGemini3Model(
+  model: string,
+  previewFeaturesEnabled = false,
+): boolean {
+  const resolved = resolveModel(model, previewFeaturesEnabled);
+  return /^gemini-3(\.|-|$)/.test(resolved);
+}
+
 /**
  * Checks if the model is a Gemini 2.x model.
  *
diff --git a/packages/core/src/routing/strategies/classifierStrategy.test.ts b/packages/core/src/routing/strategies/classifierStrategy.test.ts
index ef0f784ee2..77bd3c40b8 100644
--- a/packages/core/src/routing/strategies/classifierStrategy.test.ts
+++ b/packages/core/src/routing/strategies/classifierStrategy.test.ts
@@ -17,6 +17,7 @@ import {
   DEFAULT_GEMINI_FLASH_MODEL,
   DEFAULT_GEMINI_MODEL,
   DEFAULT_GEMINI_MODEL_AUTO,
+  PREVIEW_GEMINI_MODEL_AUTO,
 } from '../../config/models.js';
 import { promptIdContext } from '../../utils/promptIdContext.js';
 import type { Content } from '@google/genai';
@@ -50,8 +51,8 @@ describe('ClassifierStrategy', () => {
       modelConfigService: {
         getResolvedConfig: vi.fn().mockReturnValue(mockResolvedConfig),
       },
-      getModel: () => DEFAULT_GEMINI_MODEL_AUTO,
-      getPreviewFeatures: () => false,
+      getModel: vi.fn().mockReturnValue(DEFAULT_GEMINI_MODEL_AUTO),
+      getPreviewFeatures: vi.fn().mockReturnValue(false),
       getNumericalRoutingEnabled: vi.fn().mockResolvedValue(false),
     } as unknown as Config;
     mockBaseLlmClient = {
@@ -61,8 +62,9 @@ describe('ClassifierStrategy', () => {
     vi.spyOn(promptIdContext, 'getStore').mockReturnValue('test-prompt-id');
   });
 
-  it('should return null if numerical routing is enabled', async () => {
+  it('should return null if numerical routing is enabled and model is Gemini 3', async () => {
     vi.mocked(mockConfig.getNumericalRoutingEnabled).mockResolvedValue(true);
+    vi.mocked(mockConfig.getModel).mockReturnValue(PREVIEW_GEMINI_MODEL_AUTO);
 
     const decision = await strategy.route(
       mockContext,
@@ -74,6 +76,24 @@ describe('ClassifierStrategy', () => {
     expect(mockBaseLlmClient.generateJson).not.toHaveBeenCalled();
   });
 
+  it('should NOT return null if numerical routing is enabled but model is NOT Gemini 3', async () => {
+    vi.mocked(mockConfig.getNumericalRoutingEnabled).mockResolvedValue(true);
+    vi.mocked(mockConfig.getModel).mockReturnValue(DEFAULT_GEMINI_MODEL_AUTO);
+    vi.mocked(mockBaseLlmClient.generateJson).mockResolvedValue({
+      reasoning: 'test',
+      model_choice: 'flash',
+    });
+
+    const decision = await strategy.route(
+      mockContext,
+      mockConfig,
+      mockBaseLlmClient,
+    );
+
+    expect(decision).not.toBeNull();
+    expect(mockBaseLlmClient.generateJson).toHaveBeenCalled();
+  });
+
   it('should call generateJson with the correct parameters', async () => {
     const mockApiResponse = {
       reasoning: 'Simple task',
diff --git a/packages/core/src/routing/strategies/classifierStrategy.ts b/packages/core/src/routing/strategies/classifierStrategy.ts
index 4edf85a351..73a1d84165 100644
--- a/packages/core/src/routing/strategies/classifierStrategy.ts
+++ b/packages/core/src/routing/strategies/classifierStrategy.ts
@@ -12,7 +12,7 @@ import type {
   RoutingDecision,
   RoutingStrategy,
 } from '../routingStrategy.js';
-import { resolveClassifierModel } from '../../config/models.js';
+import { resolveClassifierModel, isGemini3Model } from '../../config/models.js';
 import { createUserContent, Type } from '@google/genai';
 import type { Config } from '../../config/config.js';
 import {
@@ -133,7 +133,11 @@ export class ClassifierStrategy implements RoutingStrategy {
   ): Promise<RoutingDecision | null> {
     const startTime = Date.now();
     try {
-      if (await config.getNumericalRoutingEnabled()) {
+      const model = context.requestedModel ?? config.getModel();
+      if (
+        (await config.getNumericalRoutingEnabled()) &&
+        isGemini3Model(model, config.getPreviewFeatures())
+      ) {
         return null;
       }
 
@@ -164,7 +168,7 @@ export class ClassifierStrategy implements RoutingStrategy {
       const reasoning = routerResponse.reasoning;
       const latencyMs = Date.now() - startTime;
       const selectedModel = resolveClassifierModel(
-        context.requestedModel ?? config.getModel(),
+        model,
         routerResponse.model_choice,
         config.getPreviewFeatures(),
       );
diff --git a/packages/core/src/routing/strategies/numericalClassifierStrategy.test.ts b/packages/core/src/routing/strategies/numericalClassifierStrategy.test.ts
index 93e75fcdb5..a5a7a2bc35 100644
--- a/packages/core/src/routing/strategies/numericalClassifierStrategy.test.ts
+++ b/packages/core/src/routing/strategies/numericalClassifierStrategy.test.ts
@@ -10,9 +10,11 @@ import type { RoutingContext } from '../routingStrategy.js';
 import type { Config } from '../../config/config.js';
 import type { BaseLlmClient } from '../../core/baseLlmClient.js';
 import {
-  DEFAULT_GEMINI_FLASH_MODEL,
-  DEFAULT_GEMINI_MODEL,
+  PREVIEW_GEMINI_FLASH_MODEL,
+  PREVIEW_GEMINI_MODEL,
   DEFAULT_GEMINI_MODEL_AUTO,
+  DEFAULT_GEMINI_MODEL,
+  PREVIEW_GEMINI_MODEL_AUTO,
 } from '../../config/models.js';
 import { promptIdContext } from '../../utils/promptIdContext.js';
 import type { Content } from '@google/genai';
@@ -46,8 +48,8 @@ describe('NumericalClassifierStrategy', () => {
       modelConfigService: {
         getResolvedConfig: vi.fn().mockReturnValue(mockResolvedConfig),
       },
-      getModel: () => DEFAULT_GEMINI_MODEL_AUTO,
-      getPreviewFeatures: () => false,
+      getModel: vi.fn().mockReturnValue(PREVIEW_GEMINI_MODEL_AUTO),
+      getPreviewFeatures: vi.fn().mockReturnValue(false),
       getSessionId: vi.fn().mockReturnValue('control-group-id'), // Default to Control Group (Hash 71 >= 50)
       getNumericalRoutingEnabled: vi.fn().mockResolvedValue(true),
       getClassifierThreshold: vi.fn().mockResolvedValue(undefined),
@@ -76,6 +78,32 @@ describe('NumericalClassifierStrategy', () => {
     expect(mockBaseLlmClient.generateJson).not.toHaveBeenCalled();
   });
 
+  it('should return null if the model is not a Gemini 3 model', async () => {
+    vi.mocked(mockConfig.getModel).mockReturnValue(DEFAULT_GEMINI_MODEL_AUTO);
+
+    const decision = await strategy.route(
+      mockContext,
+      mockConfig,
+      mockBaseLlmClient,
+    );
+
+    expect(decision).toBeNull();
+    expect(mockBaseLlmClient.generateJson).not.toHaveBeenCalled();
+  });
+
+  it('should return null if the model is explicitly a Gemini 2 model', async () => {
+    vi.mocked(mockConfig.getModel).mockReturnValue(DEFAULT_GEMINI_MODEL);
+
+    const decision = await strategy.route(
+      mockContext,
+      mockConfig,
+      mockBaseLlmClient,
+    );
+
+    expect(decision).toBeNull();
+    expect(mockBaseLlmClient.generateJson).not.toHaveBeenCalled();
+  });
+
   it('should call generateJson with the correct parameters and wrapped user content', async () => {
     const mockApiResponse = {
       complexity_reasoning: 'Simple task',
@@ -120,7 +148,7 @@ describe('NumericalClassifierStrategy', () => {
       );
 
       expect(decision).toEqual({
-        model: DEFAULT_GEMINI_FLASH_MODEL,
+        model: PREVIEW_GEMINI_FLASH_MODEL,
         metadata: {
           source: 'NumericalClassifier (Control)',
           latencyMs: expect.any(Number),
@@ -146,7 +174,7 @@ describe('NumericalClassifierStrategy', () => {
       );
 
       expect(decision).toEqual({
-        model: DEFAULT_GEMINI_MODEL,
+        model: PREVIEW_GEMINI_MODEL,
         metadata: {
           source: 'NumericalClassifier (Control)',
           latencyMs: expect.any(Number),
@@ -172,7 +200,7 @@ describe('NumericalClassifierStrategy', () => {
       );
 
       expect(decision).toEqual({
-        model: DEFAULT_GEMINI_FLASH_MODEL, // Routed to Flash because 60 < 80
+        model: PREVIEW_GEMINI_FLASH_MODEL, // Routed to Flash because 60 < 80
         metadata: {
           source: 'NumericalClassifier (Strict)',
           latencyMs: expect.any(Number),
@@ -198,7 +226,7 @@ describe('NumericalClassifierStrategy', () => {
       );
 
       expect(decision).toEqual({
-        model: DEFAULT_GEMINI_MODEL,
+        model: PREVIEW_GEMINI_MODEL,
         metadata: {
           source: 'NumericalClassifier (Strict)',
           latencyMs: expect.any(Number),
@@ -226,7 +254,7 @@ describe('NumericalClassifierStrategy', () => {
       );
 
       expect(decision).toEqual({
-        model: DEFAULT_GEMINI_FLASH_MODEL, // Score 60 < Threshold 70
+        model: PREVIEW_GEMINI_FLASH_MODEL, // Score 60 < Threshold 70
         metadata: {
           source: 'NumericalClassifier (Remote)',
           latencyMs: expect.any(Number),
@@ -252,7 +280,7 @@ describe('NumericalClassifierStrategy', () => {
       );
 
       expect(decision).toEqual({
-        model: DEFAULT_GEMINI_FLASH_MODEL, // Score 40 < Threshold 45.5
+        model: PREVIEW_GEMINI_FLASH_MODEL, // Score 40 < Threshold 45.5
         metadata: {
           source: 'NumericalClassifier (Remote)',
           latencyMs: expect.any(Number),
@@ -278,7 +306,7 @@ describe('NumericalClassifierStrategy', () => {
       );
 
       expect(decision).toEqual({
-        model: DEFAULT_GEMINI_MODEL, // Score 35 >= Threshold 30
+        model: PREVIEW_GEMINI_MODEL, // Score 35 >= Threshold 30
         metadata: {
           source: 'NumericalClassifier (Remote)',
           latencyMs: expect.any(Number),
@@ -306,7 +334,7 @@ describe('NumericalClassifierStrategy', () => {
       );
 
       expect(decision).toEqual({
-        model: DEFAULT_GEMINI_FLASH_MODEL, // Score 40 < Default A/B Threshold 50
+        model: PREVIEW_GEMINI_FLASH_MODEL, // Score 40 < Default A/B Threshold 50
         metadata: {
           source: 'NumericalClassifier (Control)',
           latencyMs: expect.any(Number),
@@ -333,7 +361,7 @@ describe('NumericalClassifierStrategy', () => {
       );
 
       expect(decision).toEqual({
-        model: DEFAULT_GEMINI_FLASH_MODEL,
+        model: PREVIEW_GEMINI_FLASH_MODEL,
         metadata: {
           source: 'NumericalClassifier (Control)',
           latencyMs: expect.any(Number),
@@ -360,7 +388,7 @@ describe('NumericalClassifierStrategy', () => {
       );
 
       expect(decision).toEqual({
-        model: DEFAULT_GEMINI_MODEL,
+        model: PREVIEW_GEMINI_MODEL,
         metadata: {
           source: 'NumericalClassifier (Control)',
           latencyMs: expect.any(Number),
diff --git a/packages/core/src/routing/strategies/numericalClassifierStrategy.ts b/packages/core/src/routing/strategies/numericalClassifierStrategy.ts
index 9bcaebf432..13428d02d9 100644
--- a/packages/core/src/routing/strategies/numericalClassifierStrategy.ts
+++ b/packages/core/src/routing/strategies/numericalClassifierStrategy.ts
@@ -12,7 +12,7 @@ import type {
   RoutingDecision,
   RoutingStrategy,
 } from '../routingStrategy.js';
-import { resolveClassifierModel } from '../../config/models.js';
+import { resolveClassifierModel, isGemini3Model } from '../../config/models.js';
 import { createUserContent, Type } from '@google/genai';
 import type { Config } from '../../config/config.js';
 import { debugLogger } from '../../utils/debugLogger.js';
@@ -134,10 +134,15 @@ export class NumericalClassifierStrategy implements RoutingStrategy {
   ): Promise<RoutingDecision | null> {
     const startTime = Date.now();
     try {
+      const model = context.requestedModel ?? config.getModel();
       if (!(await config.getNumericalRoutingEnabled())) {
         return null;
       }
 
+      if (!isGemini3Model(model, config.getPreviewFeatures())) {
+        return null;
+      }
+
       const promptId = getPromptIdWithFallback('classifier-router');
 
       const finalHistory = context.history.slice(-HISTORY_TURNS_FOR_CONTEXT);
@@ -177,7 +182,7 @@ export class NumericalClassifierStrategy implements RoutingStrategy {
         );
 
       const selectedModel = resolveClassifierModel(
-        config.getModel(),
+        model,
         modelAlias,
         config.getPreviewFeatures(),
       );